Hi, salter,
unfortunately you didn't say which browser you are using.
Therefore here in Chrome.

With CTRL-Shift-I you start the Development tool.

Then you start exploring.

You see here, that the "question and answer" area has a class ".question-container"


and at the right you see the actual values.


Just overwrite these values in your "custom.css" of your extended theme.

Next:
Here you see that the class ".form-control" is affected.

And also you see the actual values:

which you overwrite by e.g. "border: 1px solid red;" or whatever.

Of course, without a little bit of knowledge in css (and HTML) it seems to be difficult, but a challenge to learn.

Best regards
Joffm